FIELD OF THE DISCLOSURE
[0001] This disclosure relates to the field of liquid level position detection, in particular
to a liquid level detection system and a liquid level detection method.
BACKGROUND OF THE DISCLOSURE
[0002] Liquid level is one of the most important and common measurement parameters in industrial
processes. The measurement of liquid level mainly refers to measurement technology
for measuring vapor-liquid, liquid-liquid and liquid-solid interfaces, which are widely
used in liquid storage equipment such as chemical, petroleum, and power plants. The
existing liquid level measurement methods include pressure level measurement methods,
floating level liquid measurement methods, capacitance liquid level measurement methods,
ultrasonic liquid level measurement methods, etc. The above measurement methods have
low resolution, large errors, or the inability to perform measurements when the liquid
density or temperature changes or when the liquid is otherwise affected by the environment.
SUMMARY OF THE DISCLOSURE
[0003] The technical problem to be solved by the present disclosure is to provide a liquid
level detection system and a liquid level detection method that can improve the accuracy
of liquid level position measurements. In order to solve the above technical problem,
embodiments of the present disclosure provide a liquid level detection system comprising
a light source, a light guiding medium, a photoelectric conversion receiver, and a
processing module. The light guiding medium has an incident surface, a first reflection
surface, and an exiting surface. The incident surface, the first reflection surface,
and the exiting surface are all planar. The first reflection surface intersects a
liquid surface, and the first reflection surface includes a first sub-reflection surface
and a second sub-reflection surface, with the liquid surface as a boundary line.
[0004] A light beam emitted by the light source is emitted into the light guiding medium
through the incident surface, then incident on the first reflection surface, and finally
emitted from the light guiding medium through the exiting surface and incident on
the photoelectric conversion receiver. The light beam is incident at the same angle
on the first sub-reflection surface, the second sub-reflection surface, and a boundary
between the first sub-reflection surface and the second sub-reflection surface.
[0005] The processing module is configured to generate a light intensity image according
to the light intensity received by the photoelectric conversion receiver and to calculate
a liquid level position according to a position of an abrupt change in the light intensity
image.
[0006] Wherein, the light beam emitted by the light source is perpendicular to the incident
surface.
[0007] Wherein, the light beam is totally reflected by the first sub-reflection surface
and reflected and refracted by the second sub-reflection surface.
[0008] Wherein, the light source is fixedly disposed relative to the light guiding medium,
and the light beam emitted by the light source is parallel light. The light beam is
simultaneously incident on the first sub-reflection surface, the second sub-reflection
surface, and a boundary between the first sub-reflection surface and the second sub-reflection
surface; or wherein the light source is mounted on a first linear moving mechanism,
and the light source is linearly moved relative to the light guiding medium by the
first linear moving mechanism to sequentially emit the light beam onto the first sub-reflection
surface and the second sub-reflection surface.
[0009] Wherein, the photoelectric conversion receiver is fixedly disposed relative to the
light guiding medium, and a light beam receiving portion of the photoelectric conversion
receiver is planar and can simultaneously receive the light beams reflected by the
first sub-reflection surface and the second sub-reflection surface; or wherein the
photoelectric conversion receiver is connected to a second linear moving mechanism,
and the photoelectric conversion receiver is linearly moved relative to the light
guiding medium by the second linear moving mechanism to sequentially receive the light
beams reflected by the first sub-reflection surface and the second sub-reflection
surface.
[0010] Wherein, the light guiding medium further has a second reflection surface, and the
light beam is reflected by the second reflection surface and then emitted through
the exiting surface.
[0011] Wherein, the first reflection surface and the second reflection surface are axisymmetric,
and the axis of symmetry of the two surfaces is perpendicular to the liquid surface.
The light beam reflected by the first reflection surface is directed parallel to the
liquid surface toward the second reflection surface, and the second reflection surface
intersects the liquid surface.
[0012] Wherein, the second reflection surface includes a third sub-reflection surface and
a fourth sub-reflection surface with the liquid surface as a boundary line. The light
beam is totally reflected by the third sub-reflection surface and reflected and refracted
by the fourth sub-reflection surface.
[0013] Wherein, the first reflection surface is perpendicular to the second reflection surface.
[0014] Wherein, the light guiding medium is a right-angle isosceles prism, two right angle
surfaces respectively form the first reflection surface and the second reflection
surface, and the exiting surface and the incident surface are formed on a hypotenuse
of the right-angle isosceles prism.
[0015] Wherein, the incident surface and the exiting surface are on the same plane.
[0016] Wherein, the light beam in the light guiding medium that is incident on the exiting
surface is perpendicular to the exiting surface.
[0017] Wherein, the light guiding medium is a right-angle isosceles prism, two right angle
surfaces respectively form an exiting surface and an incident surface, and the first
reflection surface is formed on a hypotenuse of a right-angle isosceles prism.
[0018] The disclosure also provides a liquid level detection method, comprising the following
steps: providing a light guiding medium having an incident surface, a first reflection
surface, and an exiting surface, wherein, the incident surface, the first reflection
surface, and the exiting surface are planar; positioning the light guiding medium
at a liquid surface, the first reflection surface intersecting the liquid surface
and the first reflection surface comprising a first sub-reflection surface and a second
sub-reflection, with the liquid surface as a boundary line; and emitting a light beam
into the light guiding medium through the incident surface, which is then incident
on the first reflection surface, and finally emitted from the light guiding medium
through the exiting surface. The light beam is incident at the same angle on the first
sub-reflection surface, the second sub-reflection surface, and a boundary between
the first sub-reflection surface and the second sub-reflection surface.
[0019] A light intensity image is generated based on the light intensity of the light beam
emitted from the exiting surface, and a position of the liquid surface is obtained
from a position of an abrupt change in the light intensity image.
[0020] Wherein, the light beam is totally reflected by the first sub-reflection surface
and reflected and refracted by the second sub-reflection surface.
[0021] Wherein, the light guiding medium further has a second reflection surface, the second
reflection surface intersecting the liquid surface, and the second reflection surface
comprising a third sub-reflection surface and a fourth sub-reflection surface with
the liquid surface as a boundary line. The light beam is totally reflected by the
first sub-reflection surface and is totally reflected by the third sub-reflection
surface and is then incident on the exiting surface. The light beam that is reflected
by the second sub-reflection surface is reflected and refracted by the fourth sub-reflection
surface, and the light beam reflected by the fourth sub-reflection surface is emitted
toward to the exiting surface.
[0022] Wherein, the exiting surface and the incident surface are both disposed parallel
to the liquid surface.
[0023] Wherein, the light beam is incident on the light guiding medium perpendicular to
the incident surface, and the light beam emitted through the exiting surface is perpendicular
to the incident surface.
[0024] Wherein, the light beam is simultaneously incident on the first sub-reflection surface,
the second sub-reflection surface, and a boundary between the first sub-reflection
surface and the second sub-reflection surface; or wherein the light beam is movably
emitted onto the first sub-reflection surface and the second sub-reflection surface
in sequence.
[0025] Wherein, the photoelectric conversion receiver can be fixedly disposed relative to
the light guiding medium and a light beam receiving portion of the photoelectric conversion
receiver can be planar, and can simultaneously receive all the light beams emitted
from the exiting surface, or wherein the photoelectric conversion receiver is disposed
to move relative to the light guiding medium, and the photoelectric conversion receiver
receives the light beam reflected by the first sub-reflection surface and the second
sub-reflection surface.
[0026] According to the liquid level detection system and the liquid level detection method
provided by the present disclosure, the light guiding medium is located at a position
of a liquid surface, and the liquid surface divides the first reflection surface into
the first sub-reflection surface and the second sub-reflection surface. When the light
beam is incident on the first sub-reflection surface and the second sub-reflection
surface, the angle of refraction is different and the light intensity loss is different,
such that the light beam incident on the photoelectric conversion receiver through
the first sub-reflection surface and the second sub-reflection surface is different.
The light intensity curve in the light intensity image generated by the processing
module has an abrupt change, where the position of the abrupt change corresponds to
the position of the boundary line between the first sub-reflection surface and the
second sub-reflection surface, which is also the position of the liquid surface. Therefore,
the position of the liquid level can be obtained according to the position of the
abrupt change in light intensity after the light beam passes through the light guiding
medium. Even if the liquid density or the temperature changes or the liquid is otherwise
affected by the environment, the light beam still has a light intensity change at
the boundary of the first and second sub-reflection surfaces, thus ensuring test accuracy.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] In order to more clearly explain the embodiments of the present disclosure or the
technical solutions relative to the prior art, the drawings used in the embodiments
or the description of the prior art will be briefly described below. Obviously, the
drawings in the following description are only some embodiments of the present disclosure.
For those skilled in the art, drawings of other embodiments can also be obtained based
on these drawings without any creative work.
Fig. 1 is a schematic view of a structure of a liquid level detection system according
to a first embodiment of the present disclosure;
Fig. 2 is a schematic view of a structure of a liquid level detection system according
to a second embodiment of the present disclosure;
Fig. 3 is a schematic view of a structure of a liquid level detection system according
to a third embodiment of the present disclosure;
Fig. 4 is a schematic diagram of a structure of a liquid level detection system according
to a fourth embodiment of the present disclosure; and
Fig. 5 is a schematic diagram of a structure of a liquid level detection system according
to a fifth embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0028] The technical solutions in the embodiments of the present disclosure will be clearly
and completely described in the following with reference to the accompanying drawings.
[0029] A liquid level detection system provided by a preferred embodiment of the present
disclosure comprises a light source 1, a light guiding medium 2, a photoelectric conversion
receiver 3, and a processing module 4. The light source 1 emits a light beam into
the light guiding medium 2, the light beam is converted by the light guiding medium
2, then emitted from the light guiding medium 2, and enters the photoelectric conversion
receiver 3. The photoelectric conversion receiver 3 can photo-electrically convert
the received light beam, that is, convert the light intensity signal into an electrical
signal. The processing module 4 analyzes the converted electrical signal to generate
a light intensity image and calculates a liquid level position according to a position
of an abrupt change in the light intensity image.
[0030] The light guiding medium 2 has an incident surface 21, a first reflection surface
22, and an exiting surface 23. The incident surface 21, the first reflection surface
22, and the exiting surface 23 are all planar, and the first reflection surface 22
intersects the liquid surface 90. The first reflection surface 22 includes a first
sub-reflection surface 22a and a second sub-reflection surface 22b having a liquid
surface 90 as a boundary line. The light beam emitted from the light source 1 is emitted
into the light guiding medium 2 through the incident surface 21, then further incident
on the first reflection surface 22, and finally emitted from the light guiding medium
2 through the exiting surface 23 and incident on the photoelectric conversion receiver
3. The light beam is incident at the same angle on the first sub-reflection surface
22a, the second sub-reflection surface 22b, and the boundary between the first sub-reflection
surface 22a and the second sub-reflection surface 22b. The processing module 4 is
configured to generate a light intensity image according to the light intensity received
by the photoelectric conversion receiver 3 and calculate the position of the liquid
surface 90 according to the position of the abrupt change in the light intensity image.
[0031] In use, the light guiding medium 2 is located at the position of the liquid surface
90, and the liquid surface 90 divides the first reflection surface 22 of the light
guiding medium 2 into the first sub-reflection surface 22a and the second sub-reflection
surface 22b. The two sides of the first sub-reflection surface 22a face the light
guiding medium 2 and air respectively, and the two sides of the second sub-reflection
surface 22b face the light guiding medium 2 and liquid respectively. The light beams
are incident on the first sub-reflection surface 22a and the second sub-reflection
surface 22b at the same angle. When the refraction angle is different, the light intensity
loss is different, and thus the light intensity of the light beam incident on the
photoelectric conversion receiver 3 via the first sub-reflection surface 22a and the
second sub-reflection surface 22b is different. The intensity curve in the light intensity
image generated by the processing module 4 has an abrupt change, where the position
of the abrupt change corresponds to the position of the boundary line between the
first and second sub-reflection surfaces, which also is the position of the liquid
surface 90. The light intensity can be determined according to the light beam passing
through the light guiding medium 2. Therefore, the position of the liquid surface
90 can obtained according to the position of the abrupt change in light intensity
after the light beam passes through the light guiding medium 2. Even if the liquid
density or temperature changes or the liquid is otherwise affected by the environment,
the light beam will still produce a change in light intensity at the boundary of the
first and second sub-reflection surfaces, thus ensuring test accuracy.
[0032] Preferably, the light source 1 is an infrared light source conducive for reception
and photoelectric conversion.
[0033] Preferably, the light beam emitted by the light source 1 is perpendicular to the
incident surface 21, which can reduce the loss of light intensity at the incident
surface 21 due to refraction and facilitate the illumination of the light beam on
the first reflection surface 22 at a predetermined angle. In other embodiments, the
light beam may be incident on the incident surface 21 at other angles. The incident
angle of the light beam on the first reflection surface 22 is preferably a critical
angle of the refractive index between the light guiding medium 2 and the air to facilitate
the refraction of the light beam at the second sub-reflection surface 22b between
the light guiding medium 2 and the liquid to increase the loss of light intensity.
[0034] The light beam is totally reflected by the first sub-reflection surface 22a and reflected
and refracted by the second sub-reflection surface 22b. The light beam is prevented
from being refracted by the first sub-reflection surface 22a, thus increasing the
difference in light intensity of the reflected beam between the first sub-reflection
surface 22a and the second sub-reflection surface 22b and making it easier to later
determine the position of the liquid surface 90 according to a position of the abrupt
change in the light intensity. Here, the angle at which the light beam is incident
on the first reflection surface 22 can be determined according to the refractive index
of the light guiding medium 2, so that the light beam is fully reflected by the first
sub-reflection surface 22a and reflected and refracted by the second sub-reflection
surface 22b.
[0035] Preferably, the light beam incident on the exiting surface 23 in the light guiding
medium 2 is perpendicular to the exiting surface 23 to reduce the light intensity
loss of the light beam at the exiting surface 23. In other embodiments, the light
beam directed at the exiting surface 23 may be emitted from the exiting surface 23
at other angles.
[0036] The exiting surface 23 and the incident surface 21 can be arranged in parallel in
order to facilitate the processing and forming of the light guiding medium 2, which
is advantageous for the emitting angle control. Further, the exiting surface 23 and
the incident surface 21 may be located on the same plane, which may further advantageously
facilitate the processing and preparation of the light guiding medium 2 and ensure
that the exiting surface 23 and the incident surface 21 are parallel to each other.
[0037] The light guiding medium 2 further has a second reflection surface 24, and the light
beam is reflected by the second reflection surface 24 and then emitted through the
exiting surface 23. The second reflection surface 24 can be used to reflect the light
beam toward the exiting surface 23. Of course, in other embodiments, the second reflection
surface 24 may not be provided, and the light beam is reflected by the first reflection
surface 22 and directly emitted through the exiting surface 23.
[0038] The first reflection surface 22 and the second reflection surface 24 are axisymmetric,
the axis of symmetry of the two is perpendicular to the liquid surface 90. The second
reflection surface 24 intersects the liquid surface 90, and the second reflection
surface 24 is divided by the liquid surface 90 to form a third sub-reflection surface
24a and the fourth sub-reflection surface 24b, with the liquid surface 90 as the boundary
line. The light beam reflected by the first reflection surface 22 is parallel to the
liquid surface 90. The light beam reflected by the first sub-reflection surface 22a
can be directed toward the third sub-reflection surface 24a, which is then incident
on the exiting surface 23. The light beam reflected by the second sub-reflection surface
22b is incident on the fourth sub-reflection surface 24b and is then incident on the
exiting surface 23. Since the axis of symmetry of the first reflection surface 22
and the second reflection surface 24 is perpendicular to the liquid surface 90, the
light beam is fully reflected by the first sub-reflection surface 22a and then fully
reflected by the third sub-reflection surface 24a. The light beam refracts and reflects
at the second sub-reflection surface 22b and also refracts and reflects at the fourth
sub-reflection surface 24b, which can increase the loss of light intensity at a position
below the liquid surface 90. This increase the light intensity difference of the light
beam at the boundary line of liquid surface 90, thereby increasing the abruptness
of the change, which is helpful to accurately obtain the position of liquid surface
90.
[0039] In this embodiment, more specifically, the light guiding medium 2 is a right-angle
isosceles prism, and the two right angle surfaces respectively form a first reflection
surface 22 and a second reflection surface 24. A hypotenuse surface is disposed parallel
to the liquid surface 90, and the exiting surface 23 and the incident surface 21 are
both formed on the hypotenuse surface of the right-angle isosceles prism. That is,
the incident surface 21 and the exiting surface 23 are on the same plane, and the
first reflection surface 22 is perpendicular to the second reflection surface 24.
The light guiding medium 2 has a simple overall structure and is favorable for processing
and forming.
[0040] Further, the light beam emitted from the light source 1 is a parallel light, and
the light beam is simultaneously incident on the first sub-reflection surface 22a,
the second sub-reflection surface 22b, and the boundary between the first sub-reflection
surface 22a and the second sub-reflection surface 22b. A light beam receiving portion
of the photoelectric conversion receiver 3 may be planar and simultaneously receive
the light beams reflected by the first sub-reflection surface 22a and the second sub-reflection
surface 22b to generate a light intensity image.
[0041] In the liquid level detection system provided in this embodiment, the light guiding
medium 2 is placed in a liquid container, and the top surface (the hypotenuse surface
of the right angle isosceles prism) of the light guiding medium 2 is located below
the light source 1 and the photoelectric conversion receiver 3 and placed parallel
to the liquid surface 90. The light source 1 and the photoelectric conversion receiver
3 are located in a straight line and perpendicular to an edge of the light guiding
medium 2. The light beam is perpendicularly incident onto the right-angle isosceles
prism and intersects with a right-angle surface, which is the first reflection surface.
When the intersection point is above the liquid surface 90 (i.e., the light beam is
incident on the first sub-reflection surface 22a) the light beam is totally reflected
at the intersection point. The light beam is totally reflected again on an opposite
side of the light guiding medium 2 (i.e., the third sub-reflection surface 24a), and
finally the light beam is transmitted through the light guiding medium 2 and received
by the photoelectric conversion receiver 3. When the intersection point is below the
liquid surface 90, the light beam is incident on the second sub-reflection surface
22b and the fourth sub-reflection surface 24b, which do not totally reflect the light
beam, causing two reflections and refractions two occur. Finally, the reflected light
is transmitted through the light guiding medium 2 and is incident on the photoelectric
conversion receiver 3. This makes the intensity of the light collected by the photoelectric
conversion receiver 3 relatively weak. The image signal is therefore abruptly changed
at the corresponding position of the liquid surface 90, and this characteristic of
the light intensity signal is reflected in the image signal acquired by the photoelectric
converter. The position of the liquid surface 90 can be determined by the output value
of the intensity signal of the photoelectric conversion receiver 3.
[0042] In the above embodiment, the light source 1 can be fixedly disposed relative to the
light guiding medium 2. As shown in Fig. 2, in a liquid level detection system provided
by the second embodiment of the present disclosure, the light source 1 can be a moveable
light source 1. The light source 1 is mounted on a first linear moving mechanism (not
shown), and the light source 1 is linearly moved relative to the light guiding medium
2 by the first linear moving mechanism to sequentially emit the light beam onto the
first sub-reflection surface 22a and second sub-reflection surface 22b. The photoelectric
conversion receiver 3 may be stationary, and the light beam receiving portion may
be planar and sequentially receive the light beams reflected by the first sub-reflection
surface 22a and the second sub-reflection surface 22b.
[0043] In the above embodiments, the photoelectric conversion receivers 3 are each fixedly
disposed relative to the light guiding medium 2, and the light beam receiving portion
is planar and can simultaneously receive the light beams reflected by the first sub-reflection
surface 22a and the second sub-reflection surface 22b. As another embodiment, the
photoelectric conversion receiver 3 can also be configured to be movable. As shown
in Fig. 3, in a liquid level detection system according to a third embodiment of the
present disclosure, the light beam emitted by the light source 1 is a parallel light,
and the light beam is simultaneously incident on a first sub-reflection surface 22a,
a second sub-reflection surface 22b, and a boundary between the first sub-reflection
surface 22a and the second sub-reflection surface 22b. The photoelectric conversion
receiver 3 is connected to a second linear moving mechanism (not shown in the figures).
The photoelectric conversion receiver 3 is driven by the second linear moving mechanism
to linearly move relative to the light guiding medium 2 to sequentially receive the
light beams reflected by the first sub-reflection surface 22a and the second sub-reflection
surface 22b. The light guiding medium 2 of the system can be the same as the first
embodiment, and details are not described herein again.
[0044] As shown in Fig. 4, in a liquid level detection system according to a fourth embodiment
of the present disclosure, the light guiding medium 2 is the same as that of the first
embodiment, and the light source 1 is mounted on a first linear moving mechanism (not
shown). The light source 1 is linearly moved by the first linear moving mechanism
to sequentially emit light beams onto the first sub-reflection surface 22a and the
second sub-reflection surface 22b. The photoelectric conversion receiver 3 is connected
to a second linear moving mechanism, and the photoelectric conversion receiver 3 is
linearly moved by the second linear moving mechanism to sequentially receive the reflection
from the first sub-reflection surface 22a and the second sub-reflection surface 22b.
The light beam, the light source 1, and the photoelectric conversion receiver 3 move
at the same speed so as to be able to correspondingly receive the reflected light
beam. The first linear moving mechanism and the second linear moving mechanism can
be driven by the same motor to ensure that the moving speeds of the two mechanisms
are the same.
[0045] As shown in Fig. 5, a liquid level detection system according to a fifth embodiment
of the present disclosure is provided. The incident surface 21 and the first reflection
surface 22 of the light guiding medium 2 are the same as those of the previous embodiment
and are not described herein again. Different from the foregoing embodiments, in this
embodiment, the second reflection surface is not disposed on the light guiding medium
2, an angle is formed between the exiting surface 23 and the incident surface 21 instead
of being disposed in parallel, and the light beam that passes through the first reflection
surface 22 is directly emitted through the exiting surface 23 after being reflected
by the first reflection surface 22. The light guiding medium 2 can be mounted on the
side of the container, and the exiting surface 23 can be located at an outer side
of the container. The photoelectric conversion receiver 3 is disposed corresponding
to the exiting surface 23, and the photoelectric conversion receiver 3 is located
outside a wall of the container. Here, if the wall of the container is made of a transparent
material, the exiting surface 23 may be located inside the container, and the light
beam emitted from the exiting surface 23 may be directed toward the photoelectric
conversion receiver 3. The exiting surface 23 and the incident surface 21 may be disposed
perpendicularly. Specifically, the light guiding medium 2 is a right-angle isosceles
prism, the two right angle surfaces respectively form an exiting surface 23 and an
incident surface 21, and the first reflection surface 22 is formed on the hypotenuse
of the right-angle isosceles prism.
[0046] The light source 1 may be fixedly disposed as in the first embodiment or may be linearly
moved as in the second embodiment, and the photoelectric conversion receiver 3 may
be fixedly disposed as in the first embodiment or may be linearly moved as in the
third embodiment.
[0047] In the linear movement mechanisms in the second to fourth embodiments described above,
various known linear movement mechanisms can be used, such as a motor-driven ball
screw mechanism, a rack and pinion mechanism, or a cylinder, etc. Referring to Fig.
1, the present disclosure further provides a liquid level detection method corresponding
to the liquid level detection system, which includes the following.
[0048] A light guiding medium 2 is provided. The light guiding medium 2 has an incident
surface 21, a first reflection surface 22, and an exiting surface 23. The incident
surface 21, the first reflection surface 22, and the exiting surface 23 are all planar.
The light guiding medium 2 is placed at the liquid surface 90, and the first reflection
surface 22 intersects the liquid surface 90. The first reflection surface 22 includes
a first sub-reflection surface 22a and a second sub-reflection surface 22b, with the
liquid surface 90 as a boundary line. The light beam is emitted onto the light guiding
medium 2 through the incident surface 21, is incident on the first reflection surface
22, and finally emitted from the light guiding medium 2 through the exiting surface
23. The light beam is incident at the same angle on the first sub-reflection surface
22a, the second sub-reflection surface 22b and the boundary between the first sub-reflection
surface 22a and the second sub-reflection surface 22b.
[0049] A light intensity image is generated according to the light intensity of the light
beam emitted from the exiting surface 23, and the position of the liquid surface 90
is obtained from a position of the abrupt change in the light intensity image. Here,
the electrical signal of the photoelectric conversion receiver 3 can be processed
by the processing module 4 to generate the light intensity image.
[0050] The light guiding medium 2 is located at the position of the liquid surface 90, and
the liquid surface 90 divides the first reflection surface 22 of the light guiding
medium 2 into a first sub-reflection surface 22a and a second sub-reflection surface
22b. The first sub-reflection surface 22a is located above the liquid surface 90,
and the two sides thereof are adjacent to the light guiding medium 2 and the air,
respectively. The second sub-reflection surface 22b is located below the liquid surface
90, and the two sides are adjacent to the light guiding medium 2 and the liquid, respectively.
When the light beams are incident on the first sub-reflection surface 22a and the
second sub-reflection surface 22b at the same angle, the angle of refraction is different
and the light intensity loss is different. Thus, the light beam emitted from the exiting
surface 23 after being reflected by the first sub-reflection surface 22a and the second
sub-reflection surface 22b are different in light intensity. On the generated light
intensity image, the light intensity curve has an abrupt change, where the position
of the abrupt change corresponds to the position of the boundary line between the
first sub-reflection surface 22a and the second sub-reflection surface 22b, which
is also the liquid surface 90. The position of the liquid surface 90 can be derived
from the position of the abrupt change in light intensity after the light beam passes
through the light guiding medium 2. Even if the liquid density or the temperature
changes or the liquid is otherwise affected by the environment, the light beam still
produces a change in light intensity at the boundary of the first sub-reflection surface
22a and the second sub-reflection surface 22b, thereby ensuring test accuracy. Here,
the light intensity emitted from the exiting surface 23 can be received by the photoelectric
conversion receiver 3, and the photoelectric conversion receiver 3 is electrically
connected to the processing module 4. The light intensity image is generated by the
processing module 4, and the position of the liquid surface 90 can be determined.
[0051] The light beam is totally reflected by the first sub-reflection surface 22a and reflected
and refracted by the second sub-reflection surface 22b. It is possible to avoid the
loss of light intensity due to refraction of the light beam at the first sub-reflection
surface 22a. Increasing the difference in light intensity of the reflected beam between
the first sub-reflection surface 22a and the second sub-reflection surface 22b is
advantageous for determining the position of the liquid surface 90 according to the
position of the abrupt change of the light intensity. Here, the angle at which the
light beam is incident on the first reflection surface 22 can be determined according
to the index of refraction of the light guiding medium 2 and the liquid, so that the
light beam is totally reflected by the first sub-reflection surface 22a, and reflected
and refracted by the second sub-reflection surface 22b.
[0052] The structure of the light guiding medium 2 can be the same as that of the first
embodiment or the fifth embodiment. In the present embodiment, the structure of the
light guiding medium 2 is as shown in Fig 1. When the light beam is received in the
light guiding medium 2 through the incident surface 21, the light beam can be incident
perpendicular to the incident surface 21 to reduce the light intensity loss of the
light beam at the exiting surface 23. The light beam directed at the exiting surface
23 may be perpendicular to the exiting surface 23 to reduce the loss of light intensity
at the exiting surface 23 of the light beam.
[0053] In this embodiment, the light guiding medium 2 further has a second reflection surface
24, and the first reflection surface 22 and the second reflection surface 24 have
an axisymmetric structure. The axis of symmetry of the two is perpendicular to the
liquid surface. The light beam reflected by the first reflection surface 22 is incident
on the second reflection surface 24 parallel to the liquid surface 90, and the second
reflection surface 24 intersects the liquid surface 90. The second reflection surface
24 includes a third sub-reflection surface 24a and a second sub-reflection surface
24b, with the liquid surface 90 as a boundary line. The light beam is totally reflected
by the first sub-reflection surface 22a, then totally reflected by the third sub-reflecting
surface 24a, and then incident on the exiting surface 23. The light beam reflected
by the second sub-reflection surface 22b is reflected and refracted on the fourth
sub-reflection surface 24b. The light beam reflected by the fourth sub-reflection
surface 24b is incident on the exiting surface 23.
[0054] The light beam can be reflected twice in the light guiding medium 2. Where the light
beam is totally reflected twice, once on the first sub-reflection surface 22a and
again the third sub-reflection surface 24a above the liquid surface of the first reflection
surface 22, the light intensity loss is relatively small. Where the light beam has
two reflections and two refractions, once on the second sub-reflection surface 22b
and again on the fourth sub-reflection surface 24b, the light intensity loss is large.
From the light intensity image generated by the light beam emitted from the exiting
surface, a position of an abrupt change of the light beam between the liquid surface
and the liquid surface can be clearly obtained, so that the position of the liquid
surface can be determined.
[0055] In this embodiment, the light beam can be simultaneously incident on the first sub-reflection
surface 22a, the second sub-reflection surface 22b, and the boundary between the two
surfaces 22a and 22b. The photoelectric conversion receiver 3 can be fixedly disposed
relative to the light guiding medium 2, the light beam receiving portion of the photoelectric
conversion receiver can be planar, and all the beams emitted from the exiting surface
23 can be simultaneously received. In other embodiments, the photoelectric conversion
receiver 3 can be disposed relative to the light guiding medium 2, the receiving surface
can be relatively small, and the photoelectric conversion receiver 3 can be linearly
moved by the linear moving mechanism to sequentially receive light reflected from
the first sub-reflection surface 22a and the second sub-reflection surface 22b. In
addition, the light source 1 may be movably disposed such that the light beam is movably
incident on the first sub-reflection surface 22a and the second sub-reflection surface
22b in sequence.
[0056] In the above embodiments, the "liquid level" is referred to as the interface between
the liquid and the gas. In other embodiments, the "liquid level" may also be the interface
between different liquids.
[0057] The above embodiments do not constitute a limitation on the scope of protection of
the technical solutions. Any modifications, equivalent substitutions and improvements
made within the spirit and principles of the above-described embodiments are intended
to be included within the scope of the technical solutions.
1. A liquid level detection system, comprising:
a light source;
a light guiding medium;
a photoelectric conversion receiver; and
a processing module, wherein:
the light guiding medium has an incident surface, a first reflection surface, and
an exiting surface,
the first reflection surface and the exiting surface are both planar,
the first reflection surface intersects a liquid surface,
the first reflection surface comprises a first sub-reflection surface and a second
sub-reflection surface, with the liquid surface as a boundary line between the first
sub-reflection surface and the second sub-reflection surface,
a light beam emitted by the light source is emitted into the light guiding medium
through the incident surface, incident on the first reflection surface, emitted from
the light guiding medium through the exiting surface, and incident on the photoelectric
conversion receiver,
the light beam is incident at a same angle on the first sub-reflection surface, the
second sub-reflection surface, and a boundary between the first sub-reflection surface
and the second sub-reflection surface, and
the processing module is configured to generate a light intensity image according
to an intensity of the light beam received by the photoelectric conversion receiver
and calculate a position of the liquid surface according to a position of an abrupt
change in the light intensity image.
2. The liquid level detection system according to claim 1, wherein the light beam emitted
by the light source is perpendicular to the incident surface.
3. The liquid level detection system according to claim 1, wherein the light beam is
totally reflected by the first sub-reflection surface and reflected and refracted
by the second sub-reflection surface.
4. The liquid level detection system according to claim 1, wherein:
the light source is fixedly disposed relative to the light guiding medium, the light
beam emitted by the light source is a parallel light, and the light beam is simultaneously
incident on the first sub-reflection surface, the second sub-reflection surface, and
the boundary between the first sub-reflection surface and the second sub-reflection
surface; or
the light source is mounted on a first linear moving mechanism, and the light source
is linearly moved relative to the light guiding medium by the first linear moving
mechanism to sequentially emit the light beam onto the first sub-reflection surface
and the second sub-reflection surface.
5. The liquid level detection system according to claim 1, wherein:
the photoelectric conversion receiver is fixedly disposed relative to the light guiding
medium, a light beam receiving portion of the photoelectric conversion receiver is
planar, and a portion of the light beam reflected by the first sub-reflection surface
and a portion of the light beam reflected by the second sub-reflection surface are
simultaneously received by the light beam receiving portion; or
the photoelectric conversion receiver is connected to a second linear moving mechanism,
and the photoelectric conversion receiver is linearly moved relative to the light
guiding medium by the second linear moving mechanism to sequentially receive a portion
of the light beam reflected by the first sub-reflection surface and a portion of the
light beam reflected by the second sub-reflection surface.
6. The liquid level detection system according to claim 1, wherein:
the light guiding medium further has a second reflection surface, and
the light beam is reflected by the second reflection surface prior to being emitted
from the light guiding medium through the exiting surface.
7. The liquid level detection system according to claim 6, wherein:
the first reflection surface and the second reflection surface are axisymmetric,
an axis of symmetry of the first reflection surface and the second reflection surface
is perpendicular to the liquid surface, and
the light beam reflected by the first reflection surface is directed parallel to the
liquid surface toward the second reflection surface, wherein the second reflection
surface intersects the liquid surface.
8. The liquid level detection system according to claim 7, wherein:
the second reflection surface comprises a third sub-reflection surface and a fourth
sub-reflection surface, with the liquid surface as the boundary line,
the light beam is totally reflected by the third sub-reflection surface and reflected
and refracted by the fourth sub-reflection surface.
9. The liquid level detection system according to claim 7, wherein the first reflection
surface is perpendicular to the second reflection surface.
10. The liquid level detection system according to claim 6, wherein:
the light guiding medium is a right-angle isosceles prism,
a first right-angle surface of the right-angle isosceles prism forms the first reflection
surface and a second right angle surface of the right-angle isosceles prism forms
the second reflection surface, and
the exiting surface and the incident surface are both formed on a hypotenuse of the
right-angle isosceles prism.
11. The liquid level detection system according to claim 1, wherein the light beam in
the light guiding medium that is incident on the exiting surface is perpendicular
to the exiting surface.
12. The liquid level detection system according to claim 1, wherein:
the light guiding medium is a right-angle isosceles prism,
a first right-angle surface right angle isosceles prism forms the exiting surface
and a second right angle surface of the right-angle isosceles prism forms the incident
surface, and
the first reflection surface is formed on a hypotenuse of the right-angle isosceles
prism.
13. A liquid level detection method, comprising:
providing a light guiding medium having an incident surface, a first reflection surface,
and an exiting surface, wherein the incident surface, the first reflection surface,
and the exiting surface are planar;
positioning the light guiding medium at a liquid surface, the first reflection surface
intersecting the liquid surface, wherein the first reflection surface comprises a
first sub-reflection surface and a second sub-reflection surface, with the liquid
surface as a boundary line between the first sub-reflection surface and the second
sub-reflection surface; and
emitting a light beam into the light guiding medium through the incident surface,
which is then incident on the first reflection surface and emitted from the light
guiding medium through the exiting surface, wherein:
the light beam is incident at a same angle at the first sub-reflection surface, the
second sub-reflection surface, and a boundary between the first sub-reflection surface
and the second sub-reflection surface,
a light intensity image is generated according to an intensity of the light beam emitted
from the exiting surface, and
a position of the liquid surface is obtained from a position of an abrupt change in
the light intensity image.
14. The liquid level detection method according to claim 13, wherein the light beam is
totally reflected by the first sub-reflection surface and reflected and refracted
by the second sub-reflection surface.
15. The liquid level detection method according to claim 14, wherein:
the light guiding medium further has a second reflection surface,
the second reflection surface intersects the liquid surface,
the second reflection surface comprises a third sub-reflection surface and a fourth
sub-reflection surface, with the liquid surface as a boundary line between the third
sub-reflection surface and the fourth sub-reflection surface,
a portion of the light beam that is reflected by the first sub-reflection surface
is totally reflected by the third sub-reflection surface and is then incident on the
exiting surface, and
a portion of the light beam that is reflected by the second sub-reflection surface
is reflected and refracted by the fourth sub-reflection surface, and a portion of
the light beam reflected by the fourth sub-reflection surface is directed toward the
exiting surface.